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Reversal of Virus‐Induced Alveolar Macrophage Bactericidal Dysfunction by Cyclooxygenase Inhibition In Vitro
Author(s) -
Laegreid W.W.,
Liggitt H.D.,
Silflow R.M.,
Evermann J.R.,
Taylor S.M.,
Leid R.W.
Publication year - 1989
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.45.4.293
Subject(s) - biology , virus , phagocytosis , in vitro , microbiology and biotechnology , alveolar macrophage , cyclooxygenase , pulmonary alveolus , zymosan , macrophage , opsonin , immunology , enzyme , biochemistry
Virus infection of alveolar macrophages (AM) both in vivo and in vitro has been associated with a decreased ability of these cells to kill bacteria, together with enhanced production of metabolites of arachidonic acid. These metabolites, especially PGE 2 , may be inhibitory to some phagocyte functions. Primary cultures of bovine AM obtained by bronchoalveolar lavage of normal cattle were infected in vitro with parainfluenza‐3 (PI3 virus) virus. Killing of Staphylococcus epidermidis by AM was determined on days 1‐4 post‐infection (p.i.) PI3 virus‐infected AM killed significantly fewer bacteria on day 4 p.i. compared to uninfected controls (12.1 ± 1.3% infected vs. 52.7 ± 7.2% controls, P ≤ 0.05). Bacterial killing by virus‐infected AM, but not control AM, was significantly enhanced on day 4 p.i. by addition of cyclooxygenase inhibitors 1 hr prior to bactericidal assay (28.0 ± 4.5% indomethacin, 36.0 ± 4.1% mefenamic acid, 38.6 ± 7.3% piroxicam, 37.0 ± 6.4% NDGA, 44.9 ± 7.7% ETYA, P ≤ 0.05). Phagocytosis of opsonized sheep erythrocytes and superoxide generation by virus‐infected AM were not significantly increased by cyclooxygenase inhibition. Phagosome‐lysosome fusion was severely impaired in virus‐infected AM. Pretreatment of virus‐infected AM with indomethacin significantly enhanced the percentage of cell expressing fusion activity. This data suggests that in vitro bactericidal dysfunction associated with virus infection of AM is partially the result of enhanced production of prostaglandins or thromboxane by AM and/or an abnormal response to normal levels of endogenously produced cyclooxygenase metabolites. The data further indicate the presence of cyclooxygenase sensitive (phagosome‐lysosome fusion) and insensitive (phagocytic) components of virus‐induced bactericidal dysfunction in AM.